The present invention is directed to tires having inner sealant layers, and in particular to tires with multiple built-in sealant layers where at least one of them is formed from sealant precursor layers.
Tire puncture is an inherent issue for rubber tires. Because of that, sealants have been developed and placed in the inner tire to minimize the impact on the puncture. Further, punctures can occur at any temperature. A single layer of sealant of low viscosity may work very well at low temperature, but at high temperatures, it might achieve a very low viscosity, which would allow it to flow and pass out of tire during use. By depleting the tire sealant, the tire looses its puncture sealing capacity. Likewise, a single layer of sealant of high viscosity may be very good for high temperature but might be almost solid at cold temperature and thus unable to flow to plug puncture in tires at cold temperature.
Tires with built-in sealant layer are known in the art. Typically, these tire sealants are peroxide containing butyl-rubber-based sealant precursor layers, such as for example, U.S. Pat. Nos. 4,895,610; 6,962,181; 7,073,550; 7,674,344; and 8,293.049; and US Patent Publication Nos. 2005/0113502 and 2005/021568, the teachings of which are all hereby incorporated by reference. Sealant layers may be of black or non-black colors and may incorporate short fibers, such as polyester or polyurethane fibers, and other filler aggregate into sealant layers to help to plug nail hole punctures.
Tires using multiple layers are known, such as U.S. Pat. No. 8,387,672 to Majumdar where multiple layers are used and the layers are based on polyurethane sealant precursor where a non-woven layer is incorporated into it. The teaching is that the non-woven material is used to prevent leakage of polyurethane sealant plugs the puncture.